Heater Core Issue

I have this 97' wrangler. Ever since I bought it, (8 months ago, 100,000 miles) it has always burned anti-freeze a little bit. You can smell it when you turn the heater on.(Every oil change its at the add line in the overflow, so I refill it a little bit) Yesterday as I was driving home I could smell anti-freeze worse than normal, so I pulled over to check it out right then and there. From the firewall there is a nipple sticking out from where the bottom of the heater core would be located. I could see anti-freeze leaking out slowly from that nipple. Is that telling me I blew the heater core? Or a gasket or something? I had a snowmobile with a fuel pump that had that on there so when you blew the gasket it would leak out that hole so you knew what it was. Im not really a heater core expert, but I know they are bad on these machines. I dont have any liquid leaking on the passager floor inside, and its not leaking badly or anything, just a few drips every know and then. The oil never has bubbles or anything in it, so Im pretty sure its not the head gasket, i think i've narrowed it down to the heater core, but I would like to fix this problem before anything bad happens to it. I just don't understand what that nipple is for. I dont have an owners manual, so If anyone could help me out that would be great.

From what you are describing, yes it would be a heater core. That black nipple is a drain for any water, or in your case coolant, that gets in the heater box to drain outside the vehicle. Also used for any water that comes off of the evaporator core if your wrangler has A/C, to drain out.